The Steam version of Halo: Campaign Evolved never lost local split-screen, it just never got switched on.
Local co-op has stuck with the Halo campaign since the original trilogy, carrying through ODST, Reach, and Halo 4. Halo 5: Guardians cut it down to Xbox Live only, drawing criticism at the time, and Halo Infinite dropped campaign co-op from launch entirely. Campaign Evolved reversed that on console, split-screen works out of the box there. On PC, co-op has only ever been official through online play.
What Was Actually Sitting in the Files
Modder JPurd123 set out to build a split-screen mod for the PC version and found something more interesting than the mod itself. The option is already flipped on in the config (bUseSplitscreen=True), and sitting alongside it are the split-screen HUD layouts, the sign-in screen, the VFX variants, and the audio parameters, all still cooked into the PC build. None of it got stripped out. It’s just never exposed in a menu.
The mod, live now on Nexus Mods, doesn’t patch the executable and isn’t a rebuild of the feature. It calls the code that’s already there through UE4SS, adding a second local player at runtime and clearing the two things stopping that player from working. One is a viewport hold that keeps an overlay locked until a player’s streaming reports ready, which a runtime-added player never satisfies on its own. The other is a HUD manager that only builds layouts for players the engine spawned itself. JPurd123’s script releases both, and the second player loads in moving and playable without anything in the base game getting altered.
Getting It Running, and Where It Falls Apart
Getting the mod working takes UE4SS’s current experimental build rather than the last stable release, since the stable version predates the engine this game runs on. The mod also ships its own settings and signature files, because UE4SS’s defaults don’t match the developer’s custom engine fork. Full steps are on the mod page, along with the one detail that actually matters: hit the hotkey to add a second local player before a mission loads, not during it. Add a player mid-mission and the result is a black, HUD-less second half that looks like a rendering bug and isn’t one.
It caps out at two despite the engine’s own config allowing for four. A third player spawns correctly and the engine lays out the extra viewport, then the mission simply never starts. Subtitles also draw across the full screen instead of splitting per half, and testing so far leans on the campaign’s earlier missions rather than the later ones.
Why the Files Even Have This
None of this confirms intent, but the more likely read is simpler than a hidden PC feature waiting on a future patch. Campaign Evolved almost certainly shares one codebase across console and PC, and this looks like nobody ran a pass to strip the platform-specific pieces before shipping. That’s the only explanation that accounts for how complete the leftovers are. A deliberately gated feature usually gets locked behind something a bit more solid than an unused config flag, it doesn’t normally come bundled with a sign-in screen and audio parameters nobody on Steam would ever see. Leaving all of that in looks less like a feature waiting for its switch and more like a port nobody bothered cleaning up.
For anyone who’s already through the story solo and wants the specifics on how it all wraps up, that’s covered separately.
